package jdbc;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class JDBCDemo6 {
    public static void main(String[] args) {

        try (
                Connection conn = DBUtil.getConnection();
                ){
            Statement statement= conn.createStatement();
            String sql=" SELECT COUNT(*) count " +
                    "FROM class c  " +
                    "JOIN student s ON s.class_id=c.id  " +
                    "WHERE c.name='1年级1班'";

            ResultSet rs=statement.executeQuery(sql);//执行查询
            while(rs.next())
            {
                int count=rs.getInt("count");
                System.out.println("人数 "+count);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }
}
